It all depends on what your goal in Martial arts is. I myself have been practicing judo & sambo over 15 years, practiced Greco-Roman wrestling for 6 years, I messed around with Gracie jiujitsu for almost a year before realizing that I was wasting my money for something judo does just as well if not better. At the moment I'm still practicing Judo and I'm looking to pick up Muay Boran to progress the complexity of my strikes and fighting style. Truthfully though, heavyweight lifting often interferes with actual Martial Art training. I found it more difficult doing martial arts training and bag work when I was heavy and muscular. My strikes weren't as fast my endurance didn't last as long as it does now. However I do currently have a balanced routine which involves 3 full body workout days @ the gym every week.
Agree with a lot you have said but disagree with the Judo / Jiu Jitsu approach. Have done both and they have very different end goals and things they try to accomplish. Higher end Jiu Jitsu is about staying on the ground and catching your opponent whereas Judo is more on the art of taking the opponent down. A mix between the two is great, but you will be lacking ground game even in the end level of Judo if you are going against Jiu Jitsu. But that's not here or there.
I also find that weightlifting interferes with MA practice, but doesn't necessarily have to. If you're going for the powerlifter, yes, it will hinder you immensely, but if you're more on the fit look, it won't damage as much if you are at low BF%. I'm 6'4'' and pretty well built, boxe at 205lbs and have a tremendous reach. Cardio becomes a problem from carrying all the weight that I do but I'm extremely flexible so the speed aint quite an issue. It's a tradeoff for sure, but it has its place, you can balance the two, especially if you're looking into MA as entertainment and not to actually compete.